It has been reported first for copolymers of carbon monoxide and propylene and then for copolymers of carbon monoxide with cyclic olefins that the recovered copolymer can show, at least in part, a spiroketal structure. See, Organometallics 1992, 11, 1766-1769, Ind. Eng. Chem. Res. 1993, 32, 986-988, and U.S. Pat. Nos. 5,041,530 and 5,106,952.
Certain types of polyketone polymers are melt processable, e.g., into fibers, but only with difficulty due to their limited thermal stability and propensity to undergo crosslinking during processing. The copolymer comprising carbon monoxide and ethylene (See European Patent Publication No. 310,171 and U.S. Statutory Invention Registration No. H983) is the prime example.